Particulate-filter systems are used in order to reduce the particulate emission due to exhaust gases from diesel engines. A rise in pressure in the exhaust system is associated with increasing loading of a particulate filter. If a specified threshold pressure value for the exhaust-gas backpressure is exceeded, a regeneration of the particulate filter (burn-off of soot particles) must be performed.
From EP 0 117 534 there is known a method for the control of exhaust-gas emission of a diesel engine, in which method, when the pressure drop in the particulate filter reaches a predetermined value, a burner is ignited after the passage of a predetermined time from the beginning of the starting of the diesel engine, and is operated during a combustion period.
This method has the disadvantage that soot particles are burned off even if the particulate filter is not yet full. In this way the particulate filter is regenerated too frequently, which leads to a higher total thermal loading of the filter and to an elevated fuel consumption for regeneration.